A 375-acre wildfire burning in a remote area near Mount Diablo State Park in Contra Costa County was 90 percent contained as of Wednesday afternoon, according to Cal Fire.
The fire started around 4 p.m. Tuesday in the area of Curry Canyon Road southwest of Morgan Territory Road on the east side of Mount Diablo.
Flames threatened some structures early on, but firefighters, including those from the San Ramon Valley Fire Protection District, were able to protect them and they were no longer in danger today.
The fire is burning in thick grass, oak woodland and moderately thick brush, Cal Fire officials said.
Rugged terrain and high temperatures with low humidity over the past few days have made fighting the fire more difficult, but low wind has helped firefighters prevent the blaze from spreading more quickly.
The wind was, however, expected to shift this afternoon, according to Cal Fire.
About 300 fire personnel were working to put out the blaze using three helicopters, two water tenders, 18 Cal Fire engines and 15 to 20 engines from local agencies. Airplanes were also ready to respond to the fire if needed.
A number of other agencies were also assisting, including the California Highway Patrol and the Contra Costa County Sheriff's Office.
So far two firefighters have been injured. One sustained a sprained ankle and the other a cut to the leg.
The cause of the fire is still under investigation.
Firefighters expect to have the blaze fully contained by Thursday.